I think that may just be a theory of why he sold it to Disney. In his own words it appears to be primarily because he wanted Star Wars to live on beyond his lifespan, and wanted to set up the transition while he is still alive and able. He was 68 years old when he penned the deal.
"For the past 35 years, one of my greatest pleasures has been to see Star Wars passed from one generation to the next. It’s now time for me to pass Star Wars on to a new generation of filmmakers. I’ve always believed that Star Wars could live beyond me, and I thought it was important to set up the transition during my lifetime."
It's easier to criticize how someone else is handling it, if you don't put yourself in the line of fire. Is he willing to potentially do worse than Rian Johnsson? If he really passed off the series due to criticism over the prequels then maybe not.
I think we agree on George's motives for the sale. But Disney didn't uphold their side and hurt his legacy.
He was more than ready to let go, like he mentioned in many interviews, but what they did was vandalizing his legacy. I don't think he expected that, and now that it happened there are strong rumors that he wants to step in and fix what was done. It's not really about it being easy to criticize work that is based on creative choice, it's about protecting something that was damaged. It's very different.